Stern Magic Rom Numbers

(Topic ID: 209258)

Stern Magic Rom Numbers


By oldschoolbob

8 months ago



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  • 33 posts
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  • Latest reply 8 months ago by Quench
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    #1 8 months ago

    I pulled out an old MPU 100 that I had in my junk drawer. I gave up on it a couple of years ago because it was so far gone. Now I’m trying to bring it back to life. I don’t have a particular game for it. I have some old ROMs from a Magic I had. Unfortunately when I pulled them out I didn’t mark where they came from (U2 and U6). I’d like to use these for testing this board but I don’t know where they go – U2 or U6.

    MA 25AROMP14
    41-934112
    0176 7929

    And

    MA 25ARP12A/U
    457951
    0150 7929

    Can someone tell me where they go?

    Thanks

    Bob

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    #2 8 months ago

    25AROMP14 goes into U2
    25ARP12A/U goes into U6

    The attached 2 page PDF is from the back of the German Orbitor 1 manual.

    Stern_ROM_Versions.pdf

    #3 8 months ago

    Thanks Quench, I can't read German but the numbers match up.

    How did you ever find that?

    Bob

    #4 8 months ago
    Quoted from oldschoolbob:

    How did you ever find that?

    I noticed one day the German Stern manuals were longer and have more detail than the English manuals including the ROM versions. Orbitor 1 being the last release contains the (almost) complete ROM list as above - the alternate Cheetah (blue cabinet) ROM version isn't listed and maybe there's others we don't yet know about.

    #5 8 months ago
    Quoted from Quench:

    I noticed one day the German Stern manuals were longer and have more detail than the English manuals including the ROM versions. Orbitor 1 being the last release contains the (almost) complete ROM list as above - the alternate Cheetah (blue cabinet) ROM version isn't listed and maybe there's others we don't yet know about.

    That's pretty cool.

    #6 8 months ago

    It's just a pity there's no effort going on to dump Pinball ROMs like whats happened with video arcade games over the past 20 years.

    A few months ago I dumped some ROMs from a friends Pinballs that turned up the later Trident ROMs listed above - the Trident version floating around is the early version. And also an earlier version of Ballys Eight Ball. The later Eight Ball ROMs on the net fix a Tilt exploit which existed on the earlier release and other earlier Bally games.

    #7 8 months ago

    Any way to check if the ROMs are working? I connected the board and all I get is a flicker. I seem to be getting activity on the CPU but no first flash. I changed the ROMs for some really bad looking ones from my old Trident and still no flicker.

    I spent most of the day checking continuity because this board was really eaten up. But I can't find any broken traces.

    Thanks

    Bob

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    #8 8 months ago

    Oh you're going to have a fun time with that one
    With the missing pads at the IC sockets, you don't know if any important through hole vias have been ripped out. It's going to take meticulous checking with the ohm meter. You also don't know if there is any accidental solder splashes underneath the IC sockets across pins and traces running between the pins.

    Have you tried the Magic ROMs in another MPU board? Presuming they're ok, they'll probably run without jumper mods in your Wild Fyre or Eight Ball.

    The fact you're getting the flicker at power on means the CPU is partially seeing the ROMs at U6 and U2. At power on the LED defaults to ON. The CPU first points to the end of the U6 ROM and grabs the location that the software starts. In Magics case it's in U2. The first thing the software does in U2 is switch the LED OFF. So this is the LED flicker you see at power on. Then it does a checksum test of both U2 and U6 ROMs. If the checksum test passes the LED will perform its first flash. If the checksum fails, the LED will not flash and the game will purposely stall.
    So your ROM checksum test is failing for whatever reason (it might even be a bad ROM).

    Remove the two ROMs and start the board. Since there's no valid software for the CPU to run it will just go off like a freight train. With your logic probe/oscilloscope you should see activity at *both* ROM sockets on all the address and data lines. Some data lines may be less active than others but they should still change state.

    #9 8 months ago

    I know the missing pads are a problem. The sockets I just replaced (U2, U6, U7, and U8) I made sure the through hole vias were good. The ones that were missing I ran a wire through the hole soldered on top and soldered to the socket leg. The other sockets ( U9, U10, and U11) were replaced before (maybe 2 years ago). I checked those with a meter by touching the top leg of the chip and the solder pad on the top of the board. I also checked for a short between chip legs. I can't guarantee anything but I didn't find any shorts or open circuits.

    The Magic ROMs seem to work OK. I put the Wild Fyre ROMs in the junk board and still only get a flicker. I then put the Magic ROMs in the Wild Fyre board and get 6 flashes (just using a bench power supply - no seventh flash).

    Tonight I'll check for activity with the ROMs removed.

    I know this is going to be a tough one but I just want to see if I can fix it and learn something along the way.

    Thanks for all your help and teaching me more everyday.

    Bob

    #10 8 months ago

    If this is a learning exercise, then it's time to have a play with your new oscilloscope
    Remove both ROMs and also the two RAM chips at U7 and U8.

    Probe all the pins at both ROM sockets. The waveforms probably won't mean much but they need to be actively pulsing. If any pins other than Ground and VCC give you a flat line wave, then you need to investigate them.

    Take snapshots of the waveforms on each pin and compare against a working board setup the same way if you can, and look for any waveforms that are rather different. Over time doing this you will start to recognise good vs suspect waveforms on the address, data and control signals.

    In terms of shorts between pins at the sockets, this is one reason I prefer to use machined IC sockets on board repairs like this. Note, however these sockets are harder to remove if ever needed.
    With a light shining behind the board you can see if there are any shorts on the top side of the board after doing rework especially if you're stitching previously damaged traces. You can also verify that the top side traces are soldered to the socket pins. This light check can't be done with standard IC sockets that lie flat against the board.
    Can you see the short I've drawn in below? - it's not between adjacent socket pins so if that's how you're checking for shorts you won't find errors like this.
    A logic probe won't indicate faults like this either because it will just tell you the pin is pulsing as you'd normally expect.

    Good luck!

    Solder whisker short under IC socket

    #11 8 months ago

    I prefer the machine sockets but I'd had problems using them with the trace between the pads shorting as in your photo. For that reason I didn't use them here.

    To be sure I'm on the right track, I pulled U2, U6, U7, U8. I checked U2 so far:
    Pins 1 through 18 all show Max Voltage 4.83 - Min. 0 to -6 MV
    P1 shows 2.04 KHz
    P2 - 4.09 KHz
    P3 - 8.1
    P4 - 016.13
    P5 - 33.33
    P6 - 62 to 71 (it's jumping around)
    P7 - 125
    P8 - 250
    P9 - 21 to 100
    P10 - 17 to 100
    P11 - 16 to 100
    P13 - 22 to 100
    P14 - 16
    P15 - 16
    P16 - 16
    P17 - 36 to 125
    P18 - 21 to 45
    P19 - 3.95 V - 255 Hz
    P20 - 3.89 V - 127.5 Hz
    P21 - 4.83 V - 510 Hz
    P22 - 3.83 V - 510 Hz
    P23 - 4.83 V - 1020 KHz
    P24 - 4.83 V - ****

    Not sure what all this means but it looks like I have activity on all the pins on U2.

    This is the first time I've used my scope other than looking at my power supply. I'm excited.

    Thank you - Thank you - Thank you.

    IMG_1316 (resized).JPG

    #12 8 months ago

    This is what I'm using as reference.

    u2 (resized).PNG

    #13 8 months ago

    I just checked U6 and got pretty much the same results - different numbers but all pins are showing activity.

    If I have activity on the ROMs sockets (without ROMs installed) does that mean the ROMs are trying to send data to the CPU or is the CPU trying to receive the data from the ROMs? The way I understand it the first flash occurs when the CPU gets the data from the ROMs.

    I was pretty sure the ROM sockets were good because there wasn't much damage in that area and didn't need any stitching. I'm not that confident with the CPU socket. Tomorrow I test U9.

    Thanks

    Bob

    #14 8 months ago

    With no ROMs/RAM installed, the readings at the address lines "A0 - A11" should be identical at both ROM locations. So should the data lines "D0 - D7".
    The only wiring difference between the two ROM sockets is pins 20 and 21. The readings on these two pins between the sockets should look about the same (pulsing), because they're based on A11 and A9 respectively but U6 uses the logically inverted versions of these signals.

    Are you familiar with binary numbering?
    With no ROMS installed, the CPU is essentially running through every address. Without going into detail, A0 should be at highest speed (you measured 250khz), A1 should be half speed of A0, A2 should be half speed of A1, A3 should be half speed of A2 and so on and so on. This appears to be what you're getting and says the address lines look ok. Although you did mention pin 6 (A2) was jumping around a bit. You might have to investigate if this signal is shorted to an adjacent track somewhere.

    What this doesn't really check is the data lines because you don't have anything on the board (ROMs) changing their state.
    Try installing ROM U2 only and check that you have activity on the data lines (D0 - D7) at both ROM locations AND at the U9 CPU.

    What kind of signal are you getting on pin 18 of the ROM sockets? Can you post a picture?

    I still think you need to check for solder shorts at each socket between pins and traces running between them. This won't be easy but will have to be done if you're getting nowhere. This is going to be tricky. For all we know there could be multiple traces with issues.

    #15 8 months ago

    Oh I forgot to mention one quick way I check for shorts:
    Using an old fashioned analog multimeter on low resistance mode, I put a meter lead on the CPU starting with signal A0 for example, then swipe the other meter lead across every other pin of the CPU. If the meter needle swings quickly on a certain pin as I'm swiping the meter lead, I then check if it's a short circuit. Then do the same for every address line, data line and control signal.
    If your digital multimeter has a tone beeper for continuity that instantly beeps you can probably achieve the same as what I do with the analog meter. i.e. it has to be something that gives you a instant feedback as your swiping to check for shorts.

    #16 8 months ago

    Earlier today I checked the Wild Fyre board at U2 and U6. (no ROMs but I forgot to remove the RAMs). The frequency was jumping all over making it hard to read anything.

    Then I started looking over the two boards and noticed the 555 timer on the junk board looks like it has a solder bridge between pins 5 and 6. You can see it in the third photo above. The Wild Fyre board does not show continuity between those pins but the junk board does.

    I didn't get any further because my friend brought me his MPU 200 that don't boot - missing the 7th flash. So I started working on that.

    I'll be back to the junker as soon as I can.

    Bob

    #17 8 months ago
    Quoted from oldschoolbob:

    Earlier today I checked the Wild Fyre board at U2 and U6. (no ROMs but I forgot to remove the RAMs). The frequency was jumping all over making it hard to read anything.

    The RAM will contain data that the CPU sees as valid instructions and will cause unpredictable behavior in the signals.

    Quoted from oldschoolbob:

    Then I started looking over the two boards and noticed the 555 timer on the junk board looks like it has a solder bridge between pins 5 and 6. You can see it in the third photo above. The Wild Fyre board does not show continuity between those pins but the junk board does.

    Good catch. These are the things you need to look for.
    This isn't your current issue though - it would have ultimately indicated a failure at the 6th LED flash when you get ROM access working.

    #18 8 months ago

    I took a break from the MPU 200.

    I started tonight by checking A0 to A7 with the scope. Frequency was jumping around badly. Then I tried the multimeter. First time I was getting just as you said - from pin 1 to pin 8 each pin was double the last pin and frequency was steady. Then I tried the scope again and still jumping.

    I just tried the meter again and now I get 80 to 84 on the first 4 pins then it goes up slightly (85 to 90) on the next pins. And it's not steady anymore.

    And I do get the same results on U6.

    You might think it strange in this day and age but I do have an analog meter (probably older than you). I put a new battery in it and it still works. I'll look for shorts tomorrow.

    Thanks for today's lessons. I really appreciate you time teaching an old dog new things.

    Bob

    #19 8 months ago

    One last thing before I quit for the night - I did the sweep test with the analog meter and came up with nothing. Then I removed the CPU and held the board up to the light to look under the socket as well as I could. With the chip removed I could pretty well see all under the socket. I was especially looking at the traces between the pads. I didn't see anything suspect. I'm fairly confident that part is OK.

    Bob

    #20 8 months ago
    Quoted from oldschoolbob:

    Then I started looking over the two boards and noticed the 555 timer on the junk board looks like it has a solder bridge between pins 5 and 6.

    Actually this short at the 555 is between pins 7 and 8. Is pin 1 also shorted the the trace running to pin 3?

    Is your CPU at U9 a known good one?

    Some things to check below - click to zoom in:
    MPU100_rework.jpg

    #21 8 months ago

    Busy today working on my friends MPU 200 - But now it's done.

    Here's some better photos of U7 and U8.

    I did some cleaning but I didn't fine anything wrong.

    I'll get back to it after dinner.

    Bob

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    #22 8 months ago

    Some very strange things tonight. After dinner I connected the scope and got some really strange reading.

    This is nothing like what I was getting yesterday. All I did was clean up around U7 and U8.

    Oops - see next post.

    Bob

    #23 8 months ago

    Oh wait - wait. I just noticed U9 is out. I took it out last night to check under it and forgot to put it back in. My bad.

    Tomorrow I'll check everything again and start over.

    This has been a rough day.

    Bob

    #24 8 months ago

    Today I checked U2 socket with the scope again (with U9 installed this time). Frequency still jumps around so I made another video . I don't know if the problem is me or the scope but it seems I was getting better results last week.

    I do understand binary numbers somewhat and that each number should be double the one to the left. But I'm not seeing that today.

    Then I checked with the meter:

    P1 = 80 KHz
    P2 = 80-81 KHz
    P3 = 82 KHz
    P4 = 84 - 85 KHz
    5 = 91
    6 = 101 - 102
    7 = 125
    8 = 121
    9 = 80 -81
    10 = same
    11 = same
    12 = same
    13 = same
    14 = 79 - 80
    15 = same
    16 = same
    17 = 81 - 82
    18 = 120 - 125
    19 = 78 - 79
    20 = same
    21 = same
    22 = same
    23 = same
    24 = 59.85 Hz

    None of the frequencies are steady - they all fluctuate except in 24.

    This evening I'll check the data lines on U2 and U9.

    Bob

    #25 8 months ago

    Tonight I installed U2, then checked with the scope:

    Pins 9, 10, 11, 13 showed 4.83 V and about 533 KHz - then it jumps around

    Pins 14, 15, 16 showed 4.71 V and about 16.36 KHz - then jumps around

    Pin 17 showed about 131 KHz then jumps.

    Then I checked U9:

    (all showed about 4.45 V)

    Pin 26 = 131 KHz then jumps
    Pins 27, 28, 29 = 16 KHz then jumps
    Pins 30, 31, 32, 33 533 KHz then jumps.

    It's difficult to take a picture while trying to get measurements but I gave it a shot. (I think pin 18 is also shown in the video above too)

    I hope this helps to explain something.

    I'll spend the rest of the evening looking for shorts.

    Bob

    IMG_1320 (resized).JPG

    #26 8 months ago

    With U2 installed, the CPU has reached the point of executing from the start of U2 which happens to have invalid code and it looks like it's caught in an endless loop by your video. This test it isn't telling us anything useful sorry.

    1) Have you verified that the CPU (U9) is good?

    2) Out of interest, what frequencies is your scope measuring on clock input pins 3 and 37 of U9?

    3) Does this scope allow you to capture and save waveforms?

    4) Is there any chance you can plug your Eight Ball ROMs into this board and see what happens? Only have U9, U2, U6 and U11 installed - leave U7, U8 and U10 removed. We are looking for the flicker and hopefully first flash.

    5) When both ROMs are installed and after being powered on a few seconds, if you briefly short pins 39 and 40 of U9 (top two leftmost pins) to manually force a reset, do you get the first LED flash?

    #27 8 months ago

    I spent most of the day (with a lot of interruptions) checking for shorts at the base of all the chips. (Didn't check U10 or U11). I didn't find anything.

    I haven't verified U9 in another game but it's new.

    Scope shows 533 KHz on U9 pin 3 and 37. Meter shows 523.2 at pin 3 and 522.9 at pin 37.

    The scope has a Run and Stop button. It also allows me to save data but it's a Text Document with a zillion lines of numbers. But I can do a screen save.

    I tried the Wild Fyre ROMs before:

    Quoted from oldschoolbob:

    The Magic ROMs seem to work OK. I put the Wild Fyre ROMs in the junk board and still only get a flicker. I then put the Magic ROMs in the Wild Fyre board and get 6 flashes (just using a bench power supply - no seventh flash).

    But I think all chips were installed then. I'll try again with only U9, U2, U6 and U11.

    I'll also try the reset tomorrow.

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    #28 8 months ago
    Quoted from oldschoolbob:

    Scope shows 533 KHz on U9 pin 3 and 37. Meter shows 523.2 at pin 3 and 522.9 at pin 37.

    Good. Clock speed going into the CPU is pretty much on the money.

    I use one of those cheap small brass wire brushes for cleaning IC legs that are blackened (I'm looking at your two 6820 PIA chips). Gently does it of course.

    If you can try the Eight Ball ROMs, Ballys ROM test is marginally different to Stern in that it runs from U6 opposed to Stern that runs it from U2.

    Couple of things to verify - most of these are probably just reflection from the camera flash.

    MPU100_U17a.jpg
    MPU100_U2a.jpg
    MPU100_U2bb.jpg
    MPU100_U11a.jpg

    #29 8 months ago

    The 8 Ball is at a friends house. I seldom play pinball but he and his friends play a lot. It's strange but I don't really enjoy playing pinball - just fixing them.

    I noticed the PIA legs looked pretty bad but never thought about a brass brush. I think I have one somewhere - I'll give it a try.

    Most of what you're seeing is the transition between the green solder mask and the bare board where the pads are. But I'll check those areas again to be sure. The way I been checking was to hold one probe on the chip leg (or top of the socket) and touch the other probe to the traces adjacent to the pad to be sure I don't have continuity. Then check the pad to be sure I do have continuity. It's a long and slow process but like you said

    Quoted from Quench:

    It's going to take meticulous checking with the ohm meter.

    I haven't checked PIAs for continuity or shorts yet. Would anything there be causing this problem?

    Thanks

    Bob

    #30 8 months ago
    Quoted from oldschoolbob:

    I seldom play pinball but he and his friends play a lot. It's strange but I don't really enjoy playing pinball - just fixing them.

    Funny about that, it's more common than you think.

    The potential short in the first picture is the one to check as there's some solder whisker definitely there - I just can't tell from the picture if it's touching the trace next to it.

    The top side of the PIAs are generally the inputs/output pins to the games peripherals - not going to affect ROM test unless one of those lines is shorted to the CPU address/data bus. The last picture in my previous post points to some CPU control signals that go to the PIA which probably need a quick visual.

    #31 8 months ago

    I spent another day looking for shorts and checking continuity. I found nothing. After dinner I came back to the shop and continued to look over the board and compared it to the Wild Fyre board. Then I put the Magic ROMs (that I been testing with) into the Wild Fyre board and tested it. All 6 flashes. Then I put ALL the chips (including the NVRAM) into the junk board. Lo and behold I got 6 flashes.

    Tomorrow I'll re-test then swap chips back one at a time to find the culprit.

    But for now we need to celebrate. I can't believe we brought this piece of junk back to life.

    Thank you.

    Bob

    #32 8 months ago

    First thing today I tested the junk board. Still boots. Then I replaced the chips one by one and checking each time. The bad chip was U7 - 6810. I looked in my parts box and didn't have another 6810. I did find a chip that looked right but the number is SCM44464P. I "Googled" that number and it said it was a memory chip. I plugged it in and it worked. Then I connected my 24 volt test rig and now I get all 7 flashes.

    I just believe we got this junk board working. It was so eaten up with corrosion I put it in my junk drawer years ago. Every once in a while I'd look at it and say it's too far gone. This time I thought I'd give it a try.

    Thanks to all your help and suggestions we got a working board.

    Next I'll replace the headers and try it in a game.

    Bob

    #33 8 months ago

    Excellent. I think that's a critical thing I forgot to make you check early on - booting the board with the ROMs, CPU and U11 installed only and having the RAM at U7, U8 and PIA at U10 all removed.

    You must be relieved

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